This invention relates to computer systems, and especially to computer systems that are employed as servers.
The systems may for instance be employed as servers for example in local area networks (LANS) or in wide area networks (WANs), telecommunications systems or other operations such as database management or as internet servers. Such servers may be used in so-called xe2x80x9chorizontally scaledxe2x80x9d applications in which tens or hundreds of corresponding servers are employed as part of a distributed system.
A typical computer employed for such purposes will comprise two or more processors mounted on a motherboard, together with power supply units (PSUs), and other components such as hard disc drives (HDDs), fans, digital video disc (DVD) players, memory modules, ethernet ports etc. One or more of the processors, the host processor(s), provides the main functions of the server, and may communicate with a number of peripheral components, including communication ports, optionally via peripheral component interconnect (PCI) bridges in order to provide server operation. One of those peripheral components, called the xe2x80x9cSouth Bridgexe2x80x9d further allows the host processors to communicate with internal devices via serial interfaces one of which transports the console interface of the processors.
In addition to the host processor(s), the system may include another processor, called the service processor or the remote management controller (RMC), which provides management functions for the system assembly. Such functions may include environmental monitoring, temperature monitoring of the enclosure, fan speed control, data logging and the like. The service processor may communicate with the host processor or with one of the host processors, and may also have one or more external communication ports so that a user or network administrator can communicate with the service processor, or can communicate with the host processor(s) via the service processor. For example, the service processor may have its own ethernet network port for direct communication to the network administrator.
Fan speed is controlled by the service processor in order to minimise the amount of vibration and noise in the neighbourhood of the equipment, and, more importantly, in order to increase the life of the fans. With proper fan speed control, it is possible to extend the life of the fans by an order of magnitude or more, so that the fan lifetime is generally equivalent to that of the computer system. This is advantageous in the case of those systems in which it may not be possible to change the fans without shutting the system down, since any change of fans will be associated with downtime of the system.
In addition, in order to reduce the amount of downtime of the system, it is desirable to enable the system to continue to function in the event of a failure of the service processor for whatever reason. However, when the service processor has malfunctioned, all system management functions that are provided by the service processor are lost.
According to one aspect of the present invention, there is provided a computer system which comprises:
(i) a host processor;
(ii) a temperature sensor for sensing temperature in or in relation to an enclosure of the system;
(iii) one or more fans for cooling the enclosure;
(iv) a service processor for providing system management functions within the computer system, including generating fan speed signals in response to temperature values detected by the temperature sensor, and generating a control signal; and
(v) a fan controller for providing a driving signal for the fan or at least one of the fans in response to the fan speed signals generated by the service processor only when the fan controller also receives the control signal from the service processor;
wherein, in the absence of the control signal from the service processor, the fan controller will alter the driving signal to increase the fan speed to a predetermined fan speed.
Thus, the system according to the invention has the advantage that, under normal circumstances, the system will operate with dynamic control of the fans, but, should the system management functions be lost due to a malfunction of the service controller, the fan speed will be increased in order to ensure adequate cooling of the system enclosure.
The control signal may, for example, simply be a voltage level that is generated on a control line from the service processor, which may be inverted, if required, depending on the design of the service processor and the requirements of the fan controller. In such a case, a pull-up resistor may be provided between the control line and a voltage rail, or a pull-down resistor provided between the control line and earth, so that the signal on the control line will be as supplied by the service processor unless and until the service processor fails, in which case the voltage on the line will be governed by the pull-up or pull-down resistor. Alternatively a switch, for example a solid state switch, may be provided that is controlled by the control signal from the service processor and whose output is sent to the fan controller.
Although the fans may be driven to any speed that will provide an adequate margin of safety from thermal damage to the equipment, the fan controller may, for example, increase the fan speed to the maximum that can be driven by the fan controller. For example, the fan controller may provide a fan driving signal as a pulse-width-modulated (pwm) signal with a pulse width varying between, for example, 0 (i.e. off) and 100% (maximum speed), in which case, the fan controller may output a 100% pulse width, i.e. a constant d.c. voltage, when no control signal is received from the service processor.
The control line from the service processor may perform a number of functions in addition to controlling the fan controller. For example it may also control a management communication device, e.g. an external port such as an ethernet port, to enable the communication device to send and receive data only when it receives the control signal from the service processor. For example, the management communication device may be used to send system management information to a remote network administrator and to receive instructions therefrom. Such an arrangement has the advantage that the system administrator will become aware of the malfunction of the service processor by virtue of the inability of the management communication device to send or receive data.
Thus, according to another aspect of the invention, there is provided a network which includes at least one computer server comprising:
(i) a host processor;
(ii) a temperature sensor for sensing temperature in an enclosure of the system;
(iii) one or more fans for cooling the enclosure;
(iv) a service processor for providing system management functions within the computer system, including generating fan speed signals in response to temperature values detected by the temperature sensor, and generating a control signal;
(v) a fan controller for providing power for driving the fan or at least one of the fans in response to the fan speed signals generated by the service processor only when the fan controller also receives the control signal from the service processor; and
(vi) a management communication device that can communicate with the service processor and with a network administrator only when it receives the control signal from the service processor;
wherein, in the absence of the control signal from the service processor, the fan controller will increase the fan speed to a predetermined fan speed.
According to yet another aspect of the invention, there is provided a method of operating a computer system which comprises:
(i) measuring air temperature in or in relation to an enclosure of the system and sending measured air temperature data to a service processor of the system;
(ii) sending fan speed signals generated by the service processor in response to the air temperature data to a fan controller together with a control signal generated by the service processor;
(iii) sending fan driving signals generated by the fan controller to at least one fan so that it is driven at a rate determined by the service processor in accordance with the measured temperature if and only if the control signal is received by the fan controller; and
(iv) sending a fan driving signal to the or at least one fan to increase the speed of the fan to a constant value if no control signal is received from the service processor by the fan controller.